The present invention relates to an improvement of the prior duplex transceiver shown in FIGS. 1 and 2. The prior transceiver, while eliminating the need for separate generation of the receiver local oscillator first injection signal, utilizes a phase and amplitude adjustment circuit, shown in FIG. 2, which is not economical. The prior adjustment circuit requires at least two or three cascaded operational amplifier stages and extra phase shifting reactance elements in order to provide its desired signal adjustment. While the isolation provided by the prior phase and amplitude adjustment circuit is substantial, this isolation advantage is obtained at a relatively high cost.